A suicide bomber has struck an Afghan army bus carrying soldiers east of the capital, Kabul, killing at least six troops, officials have said.

The spokesman for the Kabul provincial police chief, Hashmat Stanikzai, said the bomber was on foot when he attacked the Afghan National Army troops on the Jalalabad highway near Tarakhail area early on Thursday.

The Taliban claimed responsibility for the blast in a message sent to local media by the group's spokesman Zabihullah Mujahid.

"As a result of the attack, six Afghan army staff were martyred and 10 others were wounded, Kabul Crime Branch Unit chief General Farid Afzail told the AFP news agency.

The attack is the first in the area of the capital for more than a week, and marks the resumption of an intensified anti-government campaign by the fighters.

Kabul has been hit by a spate of deadly attacks in recent weeks, heightening concerns that Afghanistan could tip into a spiral of violence as the US-led military presence declines.

NATO's force in Afghanistan will change on December 31 from a combat mission to a support role, with troop numbers cut to about 12,500 - down from a peak of 130,000 in 2010.

Fighters have targeted foreign guest houses, embassy vehicles, US troops and Afghan army buses in Kabul over the past month, undermining claims that the insurgency is weakening as NATO's 13-year war ends.